This invention relates to a heat exchanger or water jacket assembly suitable for use with water heaters and in particular to instantaneous gas fired water heaters to provide hot water on demand, and a method of manufacturing the same.
Approximately 30% of the world""s hot water heaters manufactured are of the xe2x80x9cstorage typexe2x80x9d, namely a water heater whereby a tank of water is heated by electricity, gas or oil fired burners. This type of water heater can be inefficient, bulky and constantly suffers from the escape of heat to the surroundings. A problem with storage water heaters is the limitation in volume of hot water they can provide at any one time.
Approximately 70% of the world""s water heaters manufactured are of the xe2x80x9cinstantaneous typexe2x80x9d where hot water is provided on demand by use of means to instantaneously heat the water as it flows through the heater. This type of water heater has been very pressure dependent with limitations on the volume of hot water it can provide on an ongoing basis. Also problems are commonly derived from difficulties in constructing and assembling cost effective, long life heat exchangers and water jackets which achieve minimum heat loss to the surroundings and maximum fluid-to-gas heat exchange surface areas.
In accordance with a first aspect of the present invention, there is provided a water jacket assembly for an instantaneous gas fired water heater, the assembly including pressed profiled plates made of copper or copper coated steel, one plate being the inverted image of the other, said plates being placed together in pairs, the pairs of plates being arranged in a parallel array to form a heat exchanger, the heat exchanger being bordered by a water jacket comprising overlapping side and end panels of copper or copper coated steel attached to the array of plates, the assembly being fused together to define a combustion chamber with discrete combusted gases and water passages within said assembly.
It is preferable that the profiled plates of the heat. exchanger are adapted to cause turbulent flow of water through the water passages, and turbulent flow of combusted gases past the exterior, the exterior also providing escape routes for condensate that in use collects on the external surfaces of the heat exchanger.
It is preferable that the water jacket has a cold water inlet and a hot water outlet, at least one gas burner being positioned within the combustion chamber whereby cold water flows through the assembly to exit as hot water.
Preferably, the at least one gas burner is positioned above the heat exchanger and the heater includes a fan that mixes gas with air and forces the gas/air mixture to the burner and, as combusted gases past the heat exchanger.
According to a further aspect of the present invention there is provided a method of manufacturing a water jacket assembly comprising pressing profiled heat exchanger plates, side panels and end panels out of copper or copper coated steel, placing two plates together, one being the inverted image of the other to form a pair of abutting plates, placing a plurality of pairs of heat exchanger plates together to form a sandwich, attaching the side panels to the sandwich and placing the end plates on each corner so that the side and end panels overlap, holding the assembly with a jig, and placing the assembly in an oven for a predetermined time to fuse the copper surfaces together to provide an integral assembly having a combustion chamber and discrete combusted gases and water passageways within said assembly.